A person excretes on average about 1.5 liters of urine per day, but this amount is not constant. For example, diuresis increases after drinking heavily and consuming protein, the breakdown products of which stimulate urine formation. On the contrary, urine formation decreases when consuming not large quantity water, with increased sweating.
The intensity of urine formation fluctuates throughout the day. More urine is produced during the day than at night. A decrease in urine formation at night is associated with a decrease in the body’s activity during sleep, with a slight drop in the amount blood pressure. Night urine is darker and more concentrated.
Physical activity has a pronounced effect on urine formation. At long work diuresis decreases. This is explained by the fact that with increased physical activity, blood flows in large quantities to the working muscles, as a result of which the blood supply to the kidneys decreases and urine filtration decreases. At the same time, physical activity is usually accompanied by increased sweating, which also helps to reduce diuresis.
Color. Urine is a clear, light yellow liquid. When it settles in the urine, a sediment forms, which consists of salts and mucus.
Reaction. The urine reaction of a healthy person is predominantly slightly acidic. Its pH ranges from 5.0 to 7.0. Urine reaction may vary depending on composition food products. When eating mixed food (animal and plant origin) human urine has a slightly acidic reaction. When eating primarily meat and other protein-rich foods, the urine reaction becomes acidic; plant foods promote the transition of the urine reaction V neutral or even alkaline.
Relative density. The density of urine is on average 1.015-1.020. It depends on the amount of liquid taken.
Compound. The kidneys are the main organ for removing nitrogenous products of protein breakdown from the body: urea, uric acid, ammonia, purine bases, creatinine, indican.
In normal urine, protein is absent or only traces of it are detected (no more than 0.03%). The appearance of protein in the urine (proteinuria) usually indicates kidney disease. However, in some cases, for example, during intense muscular work (long-distance running), protein may appear in the urine of a healthy person due to a temporary increase in the permeability of the membrane of the choroidal glomerulus of the kidneys.
Among the organic compounds of non-protein origin in the urine there are: salts of oxalic acid, which enter the body with food, especially plant foods; lactic acid released after muscle activity; ketone bodies formed when the body converts fats into sugar.
Glucose appears in the urine only in cases when its content in the blood is sharply increased (hyperglycemia). The excretion of sugar in the urine is called glucosuria.
The appearance of red blood cells in the urine (hematuria) is observed in diseases of the kidneys and urinary organs.
The urine of a healthy person and animals contains pigments (urobilin, urochrome), which determine its yellow color. These pigments are formed from bilirubin in bile in the intestines and kidneys and are secreted by them.
A large amount of inorganic salts is excreted in the urine - about 15-25 g per day. Sodium chloride, potassium chloride, sulfates and phosphates are excreted from the body. The acidic reaction of urine also depends on them.
Excretion of urine. The final urine flows from the tubules into the pelvis and from it into the ureter. Movement of urine through the ureters bladder carried out under the influence of gravity, as well as due to the peristaltic movements of the ureters. The ureters, entering the bladder obliquely, form a kind of valve at its base that prevents the reverse flow of urine from the bladder. Urine accumulates in the bladder and is periodically expelled from the body through urination.
The bladder contains so-called sphincters or sphincters (ring-shaped muscle bundles). They tightly close the outlet of the bladder. The first of the sphincters - the sphincter of the bladder - is located at its exit. The second sphincter - the urethral sphincter - is located slightly lower than the first and closes the urethra.
The bladder is innervated by parasympathetic (pelvic) and sympathetic nerve fibers (hypogastric). Excitation of sympathetic nerve fibers leads to increased peristalsis of the ureters, relaxation of the muscular wall of the bladder and increased tone of its sphincters. Thus, stimulation of the sympathetic nerves promotes the accumulation of urine in the bladder. When parasympathetic fibers are stimulated, the wall of the bladder contracts, the sphincters relax and urine is expelled from the bladder.
Urine continuously flows into the bladder, which leads to increased pressure in it. An increase in pressure in the bladder to 1.177-1.471 Pa (12-15 cm of water) causes the need to urinate. After urination, the pressure in the bladder decreases to almost 0.
Urination is a complex reflex act consisting of simultaneous contraction of the bladder wall and relaxation of its sphincters. As a result, urine is expelled from the bladder.
An increase in pressure in the bladder leads to excitation of the mechanoreceptors of this organ. Afferent impulses enter the spinal cord to the center of urination (II-V segments of the sacral region). From the center, along the efferent parasympathetic (pelvic) nerves, impulses go to the bladder muscle and its sphincter. A reflex contraction of the muscle wall and relaxation of the sphincter occurs. At the same time, from the center of urination, excitation is transmitted to the cerebral cortex, where a feeling of the urge to urinate occurs. Impulses from the cerebral cortex travel through the spinal cord to the urethral sphincter. Urination occurs. The influence of the cerebral cortex on the reflex act of urination is manifested in its delay, intensification, or even voluntary invocation. In children early age there is no cortical control of urinary retention. It is produced gradually with age.
Urine is a human waste product secreted by the kidneys, which is an indicator of the state of his health. She plays important role in maintaining the constancy of the internal environment and removing toxins and salts from the body. If there are any abnormalities in the functioning of the body, the properties and composition of urine may change.
What is urine?
Urine is a biological fluid formed in the excretory organs as a result of the filtration of blood and the release of metabolic products and water from it. This process occurs in the nephrons, an integral part of the kidneys. consists of a glomerulus, a surrounding capsule, tubules and tubules.
A ureter emerges from each kidney, through which urine enters the bladder, from where it is excreted from the body through the urethra.
Mechanism of formation of primary urine
Urine is formed in several stages:
- Filtration.
- Reabsorption (reabsorption).
The filtration process occurs directly in the nephrons. Blood with substances dissolved in it enters the nephron glomerulus, where, due to the difference in pressure, it is filtered. As a result, primary urine is formed. It contains water, mineral salts, nitrogenous compounds (urea, ), glucose, amino acids, and toxins. During the day, an average of 180 liters of primary urine is released. Where does she go?
Thanks to reabsorption, it is almost completely absorbed back into the blood through the nephron tubules. Normally, no nutrients should be excreted in urine.
As a result, secondary urine is formed containing water, sodium, potassium, hydrogen, etc. ions. The body no longer needs these components; they are the ones that enter the ureter.
If we compare primary and secondary urine, the first is similar in composition to blood plasma, while the second contains toxins and substances that are present in excess in the blood.
Normal indicators and composition of urine
The functioning of the body is assessed by determining the composition of urine, which affects its properties. There are physical and Chemical properties urine.
Structure of the released liquid
On a note! Urine also has the formula: (NH2)2CO
Of the inorganic substances in urine, there are ions of sodium, calcium, potassium, magnesium, chlorine, and sulfates. Their percentage depends on your diet. Normally, the most mineral substance in urine is sodium – 0.35%. The percentage of sulfates is 0.18%, potassium and phosphates are 0.15% each.
What should not be in urine:
- red blood cells;
- squirrel;
- Sahara;
- acetone;
- mucus;
- microorganisms.
Composition of urine:
| Index | Norm |
|---|---|
| Urea | 233-331 m mol/day |
| Creatinine | 13.2-17.6 m mol/l in men 7.1-13.2 m mol/l in women |
| Creatine | 84-1443 µmol/l in men 145-2061 µmol/l in women |
| Diastasis | up to 44 mg/l |
| Lactic acid | 178-1700 µmol/day |
| Uric acid | 0.27-0.70 g/day up to 0.43 g for vegetarians |
| Ammonia | 20-70 µmol/l |
| Bile acids | 0.46-0.87 µmol/day |
| Sodium | 95-310 mmol/day |
| Potassium | 3.8 to 5 mmol |
| Iron | 0.005–0.3 mg/g |
| Copper | 0.01–0.07 mg/g |
| Selenium | 0.015–0.06 mg/g |
| Cobalt | 0.00025–0.002 mg/g |
| Manganese | 0.00075–0.003 mg/g |
| Aluminum | 0–0.04 mg/g |
| Protein | 0.033 g/l |
| Glucose | 2.8-3.0 mmol/day; in pregnant women 6 mmol/day |
| Ketone bodies (acetone) | 0.17-1.7 mmol/day |
| Albumen | 1.64-34.2 mg/day |
| Bilirubin | absent |
| Urobilinogen | 5-10 mg/lu children up to 2 mg |
| 17-ketosteroids | in men 22.9-81.1 mmol/day in women 22.2-62.4 mmol/day |
| Red blood cells | men have no women 1-3 per sample |
| Columnar epithelium | 0-2 |
| 1-3 | |
| Leukocytes | 0-1 for men0-12 for women |
| Hemoglobin | absent |
| Cylinders | absent, only hyaline casts may be present, 1-2 per sample |
| Bacteria | none |
| Mushrooms | none |
| Slime | absent |
Chemical indicators
The chemical properties of urine are affected by its composition. The following characteristics depend on it:
- environmental reaction;
- transparency;
- density.
The reaction of urine is neutral, closer to slightly acidic, which is due to the concentration of hydrogen ions. This indicator depends on the dietary habits: for vegetarians it is alkaline, but when eating meat it becomes acidic. In children, urine is acidic at birth, but after 6 days it becomes alkaline.
Normally, urine is transparent, regardless of color, but with an excess of various salts, protein, pus,... Salt precipitates form a precipitate, which disappears when heated or added with various reagents.
One of important properties urine - foaminess. urine does not foam; unstable foam may form.
The density of urine depends on the concentration of sodium and urea salts in it. This figure should not be lower than 1018 g/l. As the temperature rises external environment the density decreases by 1 g/ml for every 3 degrees.
There is a relationship between the color and density of urine. The lighter it is, the less dense it is. More concentrated is characterized by high density and is most often accompanied by dehydration.
Main indicators of urine status:
Physical properties
Physical properties help evaluate urine by external signs. These include:
- smell;
- color;
- volume.
Urine does because it contains ammonia. When exposed to oxygen, ammonia oxidizes and the odor becomes more pungent.
The color of urine is normally light yellow, which is due to the presence of bile pigments. The more fluid a person drinks, the lighter his urine becomes. With an increase in sweating, accompanied by a decrease in urination, the concentration of bile pigments increases, as a result of which the color of the urine becomes darker. Color may change when taking medications.
During the day, the human body normally produces 1.5-2 liters of urine. This volume depends on the drinking regime and weather. In winter, a person produces more urine, and in summer, some of the moisture is lost as a result of sweating. The ratio of fluid consumed and excreted is called diuresis.
Urine is a biological fluid that is formed in the kidneys as a result of the removal of substances dissolved in it - waste products - from the blood plasma. The amount of urine over a certain period of time is called diuresis. can be daily, hourly or minute. Calculating this indicator, as well as determining certain properties of urine, can help in the diagnosis of many diseases of internal organs.
Photo 1. The level of urine can be used to judge the level of work of the whole organism. Source: Flickr (Ric Sumner)
What is urine
Urine is produced in nephrons - these are the structures from which,actually, consists of a kidney. In the nephrons, or rather, its capillaries, blood is filtered, getting rid of unnecessary metabolic products, and enters the renal pelvis, and then from there hits into the bladder along the ureters. After the bladder is full, the urge to urinate occurs and urine is expelled: the bladder contracts, the sphincter holding urine relaxes and urine is pushed out through the urethra.
Mechanism of urine formation
This is interesting! A nephron is a functional unit of the kidney, consisting of one renal corpuscle (glomerulus) and a system of tubules. The renal corpuscle consists of a capillary glomerulus and a capsule. This is where filtering takes place. The transformation of primary urine into secondary urine occurs in the tubules.
Urine formation looks like this:
Along the adductor arteriole the capillaries of the renal corpuscle receive blood, which is filtered here. Then The ultrafiltrate moves along the nephron, and the remaining blood components are carried out by the efferent arteriole. Reabsorption occurs in the tubules useful substances into the blood and excretion of harmful substances into the urine. This happens thanks to special epithelial cells that ensure the transport of molecules.
For example, some tubular cells are responsible for the absorption of glucose. At normal concentrations in the blood, all glucose is absorbed back and is not contained in secondary urine. A similar process occurs with amino acids.
The difference in osmotic pressure between the ultrafiltrate and blood allows removal from the latter or water. Ultimately, final urine is formed, which is excreted from the kidneys through the ureters.
Thus, in the process of formation, urine passes through two phases: primary and secondary.
Primary urine
Its composition is very close to blood plasma, this is the so-called plasma ultrafiltrate. It is formed in the renal glomeruli by filtering blood that enters here through a system of thin capillaries. The cells of the renal corpuscle form a kind of filter that does not allow large molecules to pass through.
Together with metabolites harmful to the body that must be removed, primary urine also contains useful substancesA. For example, glucose is a small molecule and therefore easily penetrates into the plasma ultrafiltrate. However, its loss is dangerous for the body, so primary urine is subject to subsequent processing.
Normally, a person produces 150-180 liters of primary urine per day.
Secondary urine
This phase is also called the final phase. She formed by reabsorption(suction) from ultrafiltrate into plasma of some substances and excretion(emphasis) in the opposite direction others.
As a result of these processes, those substances that the body should not lose through urine enter the blood from the ultrafiltrate, and those that did not pass through the filter, but must be removed, are removed. Then final urine is excreted from the body in a volume of 1.5 - 2 liters per day.
What can be diagnosed by the composition of urine
Analysis of urine can help in diagnosing many diseases. First of all, this pathology of the kidneys and urinary system. For example, this can be found glomerulonephritis, pyelonephritis, damage to the ureters or urethra, urolithiasis.
In addition, urine analysis is used in the diagnosis of a number of diseases of other organs and systems. For example, you can suspect jaundice when it appears in the urine, diabetes mellitus with glucosuria, myeloma with proteinuria.
It is a mandatory study performed when a patient is admitted to a hospital.
According to the composition of urine, it physical properties conclusions can be drawn about the condition and functioning various systems body.
Norm of physical properties
Physical properties of diagnostic value include color, smell and volume urine.
Smell
Normally, urine has a characteristic pattern due to the presence of ammonia in it. Under various pathological conditions, this parameter may change. For example, the sweetish smell of acetone can appear with diabetes, a putrid smell with a urinary tract infection, and a fecal smell with E. coli multiplying in the urethra.
Color
This biological fluid has light yellow color. It may vary depending on weather conditions and drinking regime. For example, in the hot season and when drinking a small amount of water, the urine becomes dark yellow. During the cold season or when drinking too much water, it may become almost transparent.
Coloration of urine may occur for a number of pathological conditions in these colors:
- Red. For gross hematuria (detection of blood in the urine).
- Dark brown. Formed during jaundice.
- White. Indicates an excess of fatty inclusions in the blood.
- Black. Formed during myoglobinuria.
- With a greenish tint. With pyuria (presence of pus in the urine).
Volume
An adult excretes throughout the day from 1.5 to 2 liters of urine. This parameter may change depending on the drinking regime and weather conditions. For example, in summer a person actively sweats, thus losing some of the moisture. In this case, he can secrete 1.2-1.5 liters of urine. In winter, urination becomes more frequent and instead of 2 liters of urine output there can be 2.5 liters. The more a person drinks, the more urine he must excrete. That is why it is not absolute numbers that are important, but the ratio of fluid consumed and excreted. Normally, these numbers are almost the same.
Chemical composition and its norm
Acidity
This indicator has the designation . Depends on the concentration of hydrogen or hydroxide ions in the liquid. Normally, the urine reaction is slightly alkaline and approximately equal to 6. However, this indicator can vary widely (from 4 to 8), which is also considered a physiological reaction to an excess or lack of ions in the blood. A change in acidity in itself cannot indicate a specific pathology.
Protein
Its appearance is allowed up to 0.03 g/l. More protein is called proteinuria. It appears in two cases:
- If the renal glomeruli are damaged;
- With excess protein in the urine (for example, myeloma).
Red blood cells
It may be normal up to 1-2 red blood cells in the field of view of the microscope. An increase in this indicator is called. It may indicate nephron damage (leached red blood cells) or urinary tract damage (normal red blood cells).
It is important! Women should not take a urine test during menstruation. During this period, a large number of red blood cells enter the urine from the vagina, which is a normal process. In this case, the analysis will be uninformative.
Sugar
There should be no glucose in the urine. Its appearance is called glucosuria. It occurs in two cases:
- If the nephron is damaged;
- If there is more than 10 mmol/l glucose in the blood.
Photo 2. Can determine sugar level general test, if necessary, conduct a study of the material collected per day. Color
Transparency (Haze)
Density
The pH of urine with a mixed diet is 5-7. The acidity of urine increases from meat foods, with severe physical activity, starvation, fevers, diabetes, tuberculosis.
The acidity of urine is reduced by plant foods, mineral water, with cystitis, severe vomiting. Changes in acidity can lead to the formation of stones.
Normal urine density is 1010 – 1025 g/l. Characterizes the concentration function of the kidneys.
P An increase in urine density occurs with a decrease in fluid intake, increased fluid loss, oliguria, and diabetes mellitus.
A decrease in urine density is observed with prolonged fasting, a protein-free diet, chronic glomerulonephritis, pyelonephritis, and diabetes insipidus.
Normally, urine is clear. Cloudy urine may be due to excess urate, phosphate, oxalate, lipids, or leukocytes in the urine.
Normal urine color ranges from straw yellow to deep yellow. It is caused by urochrome, urobilin, etc.
Increasing Intensity Coloring of urine occurs with edema, diarrhea, and vomiting.
Reddish color(meat slops) – for hematuria, hemoglobinuria.
Greenish yellow color– with obstructive jaundice and the presence of pus in the urine.
Greenish-brown color(beer color) – with parenchymal jaundice.
Dark, almost black color– with hemolytic anemia (hemoglobinuria).
whitish color– with phosphaturia and lipuria (lipids).
Urine color changes with certain medications
Red color- from antipyrine, amidopyrine.
Pink color – from taking aspirin, also carrots, beets.
Brown color – from taking phenol, cresol, activated carbon.
The main component of urine is water (1-2 l/day), in which the dry residue (60 g/day) is dissolved. The dry residue is represented by organic and inorganic compounds.
Daily human urine contains 47 – 65 g solids. Of these, approximately two thirds are from organic compounds(products of catabolism of proteins, fats, carbohydrates, vitamins, hormones and their metabolites, pigments) and one third part - on inorganic substances(sodium, potassium, calcium, chlorides, phosphates, bicarbonates).
Fine
Urea– the main organic component of urine (20 – 35 g/day). The content of urea excreted in the urine increases with the consumption of food rich in proteins, with increased breakdown of proteins in the body; decreases – with liver diseases, renal dysfunction.
Amino acids– in the daily amount of urine is about 1.1 g. An increase in the excretion of amino acids in the urine occurs with liver diseases, reabsorption disorders in the renal tubules, and with congenital disorders of amino acid metabolism (for example, with phenylketonuria, the content of the amino acid phenylalanine and its keto derivatives in the urine increases).
Creatine– practically absent in the urine of adults; it appears in it if the level of creatine in the blood serum exceeds 0.12 mmol/l (for example, when consuming significant amounts of creatine with food, in early childhood, in the elderly, as well as with progressive muscular dystrophy).
Creatinine- the end product of nitrogen metabolism, formed in muscle tissue from creatine phosphate. The daily release of creatine (in men 18–32 mg/kg body weight, in women 10–25 mg/kg body weight) is a constant value and depends mainly on muscle mass.
Uric acid– end product of purine metabolism (0.5 – 1.0 g/day). The excretion of uric acid in the urine increases when eating foods rich in nucleoproteins, with gout, with leukemia, hepatitis, and excess steroids; decreases with a diet poor in purines.
Sodium chloride is the main mineral component of urine solids (8 – 15 g/day). An increase in the amount of NaCl in daily urine can be observed with excessive consumption of salts in food and with the introduction of large quantities of saline into the body; reduction – in some diseases (chronic nephritis, rheumatism, diarrhea).
Ammonia excreted in urine in the form of ammonium salts. Their content in human urine reflects the acid-base state. With acidosis, the amount of ammonium salts in the urine increases, with alkalosis it decreases.
Lactic, pyruvic, oxalic, succinic, acetic, propionic, valeric and other acids. Their excretion in urine does not exceed 1 g/day. An increase in their concentration is observed with intense muscle load, hypoxia, diabetes mellitus, and fasting.
Various substances are excreted from the body in urine toxic substances , after their neutralization in the liver by conjugation with sulfuric or glucuronic acids.
Human urine
Amount of urine. On average, a person excretes about 1.5 liters of urine per day. However, this amount is not constant and fluctuates within fairly wide limits. For example, the amount of urine excreted increases after drinking a large amount of liquid, consuming significant amounts of protein, the breakdown products of which increase the activity of the kidneys. Conversely, urine production decreases when a person consumes little fluid, when food contains little protein, or when excessive sweating occurs and a significant amount of water is lost through sweat.
The intensity of urine formation fluctuates throughout the day. During the day, urine is produced more intensely than at night, even if a person drinks the same amount of water at night as during the day.
Rice. CRYSTALS OF SALTS INCLUDED IN NORMAL URINE. 1 - phosphate: 2 - acidic ammonium urate; 3 - carbon dioxide; 4 - uric acid; 5-oxalate.
Urine
The smallest amount of urine is produced between 2 and 4 am. A decrease in urine formation at night is associated with a decrease in organ activity during sleep and with a slight drop in blood pressure, due to which the pressure in the kidneys also decreases and filtration decreases.
Physical work also affects urine formation. During prolonged physical work, the amount of urine excreted decreases, firstly, because the capillary network of the muscles opens and flows to the muscles, and thereby the blood supply to the kidneys decreases, and secondly, because physical work is usually accompanied by sweating, and this also leads to to a decrease in urine formation.
Urine color
Urine is a clear, light yellow liquid. When standing, sediment forms. The resulting turbidity consists of salts and mucus.
Urine reaction. With a large mixed meal, the urine of a healthy person has a slightly acidic reaction. The reaction of urine is not constant and changes depending on nutrition.
When consuming predominantly meat foods and other protein-rich substances, the urine reaction becomes acidic; plant foods cause some alkalization and the urine reaction becomes neutral or even alkaline.
Specific gravity of urine. The specific gravity of urine varies depending on the amount of fluid taken. A large amount of water consumed causes a drop in specific gravity; on the contrary, when water supply is limited specific gravity rises. On average, the specific gravity of urine is 1015-1020.
The composition of urine includes nitrogen-containing protein breakdown products, soda (Fig.) and some acids. On average, 60 g of salts are excreted in urine per day.
In table The approximate amounts of some substances that make up urine are given.
It is excreted primarily in the composition of urea, which accounts for approximately 90% of the urea formed as a result of protein breakdown.
Normal urine does not contain protein, since, being a colloid, it does not pass through the walls of the capillaries. The appearance of protein in the urine indicates kidney disease. Protein can appear in the urine either as a result of a pathological change in the permeability of the capillary walls, when they begin to leak protein into the urine, or due to inflammatory processes in the kidneys.
Protein on a short time may appear in the urine of a healthy person during great physical stress. This is especially true for athletes who participate in running. The appearance of protein in the urine is the result of a temporary change in the permeability of the renal vascular system. Soon, normal kidney function is restored, and the protein in the urine disappears in these people.
The appearance of protein in the urine is called albuminuria.
Sugar in the urine can appear in both patients and healthy people. In sick people, the release of sugar in the urine is observed when they have diabetes. In healthy people, sugar appears in the urine after consuming large amounts of sugar. The excretion of sugar in the urine is called glucose in the urine.
Human urine tablenumber of substances included in the composition urine (in urine excreted in 24 hours)
The appearance of blood in the urine, or hematuria, is observed with hemorrhages in the area of the kidneys or urinary organs. Normal integral part urine are pigments - urobilin and urochrome, which give urine its characteristic color. Urine pigments are formed in the intestines and kidneys from bile pigments, which in turn are formed from the breakdown products of hemoglobin.